mrwody 1 Posted November 25, 2013 Share Posted November 25, 2013 Hi, seems to be a problem in the OFP regarding the distance from ETP. They are always 10nm off. In the ETOPS section the distance from ETP to next waypoint differs by 10nm to the distance in the waypoint-log. I marked the relevant sections in the attachment. Thanks for looking into that! -mrwody ofp.pdf Link to comment Share on other sites More sharing options...
CensoringUsers 2 Posted November 27, 2013 Share Posted November 27, 2013 I'm not sure but could it be rounding? Link to comment Share on other sites More sharing options...
mrwody 1 Posted November 28, 2013 Author Share Posted November 28, 2013 Not really, it's always and ever exactly 10nm difference, that for sure is a bug in my opinion :-) Link to comment Share on other sites More sharing options...
Pierre95 14 Posted November 28, 2013 Share Posted November 28, 2013 Hello Gents, Could you send me the complete OFP because I only saw 1EO decomp. for ETP1. I would like to see the 3 ETP1 scenario Best Regards Pierre Link to comment Share on other sites More sharing options...
mrwody 1 Posted November 29, 2013 Author Share Posted November 29, 2013 Hello Pierre, sure attached the whole OFP. But calculated profile with 2 scenarios. As you can see ETP1 and 2 are both 10nm miles off. Thank you! Best Regards Constantin AUA736 FIMP-YPPH (23 Nov 1500 UTC).pdf Link to comment Share on other sites More sharing options...
bcars 23 Posted November 29, 2013 Share Posted November 29, 2013 One observation here. The ETP1 / 2 in the NavLog are for cruise altitude / speed, whereas the 1EO and 1EO Decomp assume a descent to a lower altitude and the winds aloft will be different so would result in a different Point. Check the Lat/Lon of the ETP1 for both 1EO and 1EO Decomp and you will see different points. Not sure if this is the reason for the difference. Odd that it is always 10nm diff from the NavLog, but could be a constant speed descent being factored in ???? Link to comment Share on other sites More sharing options...
Pierre95 14 Posted November 29, 2013 Share Posted November 29, 2013 Hello, Here is an OFP wich uses etops. As you can see there is no 10 nm difference because a constant speed descent is took into account. I think someone as Doug could give you a better answer as he is real life dispatcher... Best Regards Pierre Link to comment Share on other sites More sharing options...
mrwody 1 Posted November 29, 2013 Author Share Posted November 29, 2013 Hello, thank you Pierre and thank you Bruce! I'm still not quite sure, why it is exactly 10nm in every case, but I guess your hints might be right. Perhaps someone can explain it to me :-) Thank you and best regards, Constantin Link to comment Share on other sites More sharing options...
Pierre95 14 Posted December 1, 2013 Share Posted December 1, 2013 Hello Constantin, The scenario kept into account in ETP calculation is always the most critical, which is 1EO + depress situation. As explained in the so good Belisar Hoxholli document part 2, this is that point which will be entered into the FMC as ETP. If depressurisation scenario occurs with all or with 1EO, the captain will have to as quickly as he can descent to FL100 for oxygen supply. The ETP entered into FMC will be good for both case. If just 1EO scenario occurs in flight, the captain have to reduce thurst to reach minimum drag speed for the actual cruise altitude.(Driftdown speed). The aircraft will descent at the best rate and fuel efficiency to the altitude at which the driftdown speed becomes the optimal speed because the air density has increases during descent and by the way increases the lift. Hope this help Pierre Link to comment Share on other sites More sharing options...
mrwody 1 Posted December 6, 2013 Author Share Posted December 6, 2013 Hello Pierre, thank you for your explanations, helps really. I did read the 2 excellent ETOPS manuals but the exactly 10nm off consufed me Thank you and best regards, Constantin Link to comment Share on other sites More sharing options...
Pierre95 14 Posted December 7, 2013 Share Posted December 7, 2013 Hi Constantin, We all have to learn every day, and me first. Reading the ETOPS manuals is the better thing you've done. Thanks to you Pierre Link to comment Share on other sites More sharing options...
Pierre95 14 Posted December 12, 2013 Share Posted December 12, 2013 Hello Gents, Christian just told me that the ETP point in flight log was wrong. It is fixed in next release. Thanks to Mrwody for report and insisting. Best Regards Pierre Link to comment Share on other sites More sharing options...
mrwody 1 Posted December 12, 2013 Author Share Posted December 12, 2013 Hi Pierre, great to hear. Thank you for your support and Christian for his work of course! Best regards, Constantin Link to comment Share on other sites More sharing options...
Recommended Posts
Archived
This topic is now archived and is closed to further replies.